synphot

library1.7.0pypypi✓ verified 86d ago

Synthetic photometry library for astronomy, providing tools to simulate observations through various bandpasses, compute count rates, and handle spectral flux densities. Current version 1.7.0, requires Python >=3.10 and Astropy. Release cadence is irregular, approximately 1-2 minor versions per year.

data serialization http-networking ai-ml observability

pip install synphot

package ↗

INSTALL

IMPORT

SIG · SYNPHOT

synphot

datapythonv1.7.0

Install

10.5s avg

Import

3548ms

Disk

301MB

Pass rate

9/ 10

Env Coverage9 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v1.7.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

glibc

py 3.10

✓ —

✓ 10s

py 3.11

✓ —

✓ 10.1s

py 3.12

✓ —

✓ 10.4s

py 3.13

✓ —

✓ 10.8s

py 3.9

✕ build_error

✓ 11.4s

301MB installed

● package 301MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

SourceSpectrum

✓ from synphot import SourceSpectrum

Main class for defining a source spectrum.

SpectralElement

✓ from synphot import SpectralElement

Main class for defining a bandpass (filter).

Observation

✓ from synphot import Observation

Class to combine source and bandpass and compute photometry.

Basic example of creating a source spectrum and a bandpass, then computing synthetic photometry.

from synphot import SourceSpectrum, SpectralElement, Observation from synphot.models import Empirical1D, BlackBodyNorm1D from astropy import units as u import numpy as np # Define a simple blackbody source spectrum bb = BlackBodyNorm1D(temperature=5000) wave = np.arange(1000, 10000) * u.AA source_spec = SourceSpectrum(bb, points=wave) # Define a Johnson V filter # (Filter throughput data can be loaded from a file or defined manually) # Example using a built-in filter from specutils or a custom one: # Here we create a simple Gaussian bandpass for demonstration from astropy.modeling.models import Gaussian1D v_filter = SpectralElement(Gaussian1D, mean=5500, stddev=500, points=wave) # Compute the observation obs = Observation(source_spec, v_filter) count_rate = obs.countrate() # counts per second print(count_rate) # Compute effective wavelength eff_wave = obs.effective_wavelength() print(eff_wave)

Debug

Known issues

breakingIn version 1.6.0, `force_flux_unit` was changed to require a unit instance, not a string. Passing a string will raise an error.

fix

Replace strings like 'flam' with astropy units: e.g., `u.erg/u.s/u.cm**2/u.AA`.

affects: >=1.6.0

deprecatedThe `countrate` method returns counts per second based on the default flux density units (FLAM). If you need counts per second in a different bandpass, specify the area explicitly.

fix

Use `Observation.countrate(area=...)` or convert units appropriately.

affects: all

gotchaWhen creating a `SourceSpectrum` from a model, the `points` argument must be in the correct wavelength unit. If omitted, the model's internal points may not match expectations.

fix

Always pass `points` with explicit units (e.g., `wave * u.AA`) when constructing from models.

affects: all

Errors

Common errors & fixes

AttributeError: module 'synphot' has no attribute 'SourceSpectrum'

synphot is sometimes confused with the older stsci_package synphot (a different library). The correct package is installed as `synphot`, but import path is `from synphot import SourceSpectrum`.

fix

Uninstall any old version (`pip uninstall synphot` and then reinstall with `pip install synphot`). Ensure you are using the correct import.

ValueError: The unit 'flam' is not recognized

In older versions, strings like 'flam' were accepted. Since 1.6.0, you must use astropy units.

fix

Use `u.erg / (u.s * u.cm**2 * u.AA)` instead of `'flam'`.

ImportError: cannot import name 'BlackBodyNorm1D' from 'synphot.models'

BlackBodyNorm1D was added in version 0.3. Ensure your version is up-to-date.

fix

Update synphot: `pip install --upgrade synphot`.

Upgrade

Version history

1.7.0latest on PyPI · released Mar 7, 2026

Audit

Dependencies

astropyrequiredCore dependency for units, FITS I/O, and cosmology.

scipyrequiredUsed for interpolation and integration.

numpyrequiredStandard math and array operations.

Agent activity

41 hits · last 30 days

node

OpenAI (training)

Resources

packagehttps://pypi.org/project/synphot/ ↗